I've recently come across a disinformation around evidence relating to school closures and community transmission that's been platformed prominently. This arises from flawed understanding of the data that underlies this evidence, and the methodologies used in these studies.
Let's look at the paper being cited here. This study published in Nature Human Behaviour examined >50,000 interventions (at fine scale) across >200 countries. The number of countries examined allowed examination of these in depth.

As the authors state, the key strength of the study is that examination across so many different contexts allowed a disentanglement of interventions. The authors used four approaches, including a case-control analysis to specifically deal with this issue.
Reassuringly all four methods used reach the same conclusion with respect to ranking. As the authors themselves state, the richness of the data across many countries allows them to disentangle effects much better. The data are available here:
A quick look through the data shows that there is sufficient separation between different interventions in different countries over time- including school closures to be able to disentangle effects. Examination of multiple interventions also reduces the possibility of confounding
Of course, this is not the only study to reach these conclusions. Here is another study by the Lancet examining school closures & openings over 131 countries that reached the same conclusion.

Such modelling studies have been consistently used to examine the impact of non-pharmaceutical interventions on R. This is valid methodology, and generally authors have been clear on where data were too limited to do this, and where data allowed effects to be disentangled.
The impact of school closures on transmission is now widely accepted, including by SAGE, as highlighted in this document.
Ironically, the same scientists who cast doubts on robust global evidence on school closures have often quoted flawed studies on symptom-based testing to claim that children & schools don't contribute substantially to or 'drive' transmission.
Much of the evidence cited to back-up claims around lack of schools 'driving' transmission is based on one or more of the following:
1. Symptom-based studies that underestimate transmission in schools & from children who are likely to be asymptomatic index cases & not identified
2. Studies where background transmission has been very low, or mitigation in schools has been in place or both
3. Studies in households at a time schools were closed
4. Studies in schools at a time school attendance was low (see PHE study)
We need robust scientific discourse that is based on the evidence presented. It is valid to critique evidence of certain forms, but this needs to be done with sufficient scrutiny of detail and a deep understanding of methodology and data.
Just want to clarify that I've included a screenshot image rather than tagging the author of the tweet directly - not to avoid a discussion around this - but rather because I was blocked by her previously when I challenged her claims around children transmitting less than adults.

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More from @dgurdasani1

3 Feb
A thread discussing recent evidence on longer gap dosing with Astra/Oxford, Pfizer, current gaps in our understanding of impacts, as well as the possible impact of new variants on vaccine effectiveness. Thread.
First, I want to say that this although thread may highlight uncertainties & gaps in current evidence I fully advocate taking the vaccine, as this will offer protection. But I also firmly believe that discussing uncertainties in evidence & transparency around data is important.
Astra/Oxford published data yesterday, suggesting that longer gaps between the 1st and 2nd dose may be associated with higher efficacy. Vaccine efficacy between 3-12 wks after a single dose was reported to be 76% with protection being similar throughout this period.
Read 24 tweets
2 Feb
Concerning data from PHE today suggesting that sequencing shows that there are 11 cases of the UK variant (B117) identified that also have the E484K mutation (the one found in the so-called South Africa and Manaus variants). This is important and concerning for many reasons. 🧵 Image
To recap the B117 ('UK variant') is defined by a number of mutations, including the 501Y mutation thought to be associated with increased transmissibility, which is also shared by the so-called South Africa (B1351) and Manaus (P1) variants.
In addition, both B1351 (SA) & P1 (Manaus) variants also have the E484K mutation. This mutation has been associated with a high level of escape of neutralising antibodies directed at previous variants in the laboratory, raising concerns about vaccine efficacy.
Read 24 tweets
30 Jan
These studies are heavily flawed, and are don't include any of the larger, and less biased studies that contradict this view. There are ample studies with larger sample sizes, including from the ONS, that show primary school children play an important role in transmission.
And completely misses the direct impact on children from Long COVID. 12% of primary school children have symptoms lasting > 5 wks. We need to look at this based on the breadth of evidence, and the design of these studies- which unfortunately even many scientists haven't done.
The ECDC paper is extremely flawed, and quotes largely studies from symptom based testing designs, which we know hugely underestimate the impact of children on transmission. And from periods when either community tranmission was low, or school attendance was low in many regions.
Read 8 tweets
26 Jan
On @BBCOS today discussing the tragedy of exceeding 100,000 COVID-19 deaths in the UK, and what led to this.

19:03 for a bit and then 19:23 onwards:

Also, a few thoughts in a thread below:
The PM said during the briefing today, that the govt did the best they could. He was 'deeply sorry' for every single death.

If every single death is a tragedy, then why didn't we treat every death as preventable?

Why did we repeatedly talk about 'tolerable deaths'?
How on earth can he say he did his best, when UK policy was almost never evidence based - and the govt invited proponents of the ideology of naturally acquired herd immunity to brief him on policy- at a point in time we urgently needed to act to prevent thousands of deaths?
Read 16 tweets
23 Jan
Thread on the recent report on the possible risk of increased death associated with the new UK variant (B117)- with a discussion of the evidence around this, and what this means.
First, there is strong evidence to support increased transmissibility of B117 - current estimates of increased transmissibility range between 30-70% - from epidemiological evidence examining the differential rate of growth of B117 with respect to other variants & increase in R
There is also evidence from PHE contact studies that the risk of transmission from those carrying the B117 variant is ~50% greater than with other non-B117 variants.
Read 27 tweets
19 Jan
Very concerning report - 47 cases of the 501Y.V2 (variant arisen from South Africa) reported in surveillance within the UK. This is the variant with the E484K mutation that has been associated with significant escape from antibodies in the laboratory. 🧵

More information on the variant here.Using plasma those infected in the 1st wave (with robust antibody responses) >90% showed reduced neutralisation with the variant and 48% showed complete escape. How this translates to vaccine response isn't clear yet.

Antibody neutralisation is only one part of the immune response. T cell adaptive responses are also important, but the early data on reduced neutralisation are concerning. We need to look carefully at vaccine effectiveness against this variant.
Read 7 tweets

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